Halong bay is a massive complex of numerous astonishing caverns created by the marine actions through millions of years. Tourists flock to this UNESCO declared world heritage site not only to admire the beautiful seascape of the magnificent limestone pillars rising above the turquoise blue water but visit the Mother Nature’s work of art inside the karst pinnacles. Many caverns in Halong were recognized as the must – visit places in term of most incredible grottos.